4. MMeettaall ccoorrrroossiioonn
galvanic corrosion
different metals
fretting corrosion
same metals in micro-movement
crevice corrosion
metals in different electrolytic fluids
22. Study Design.
A prospective study of tissue
surrounding spinal
instrumentation was
performed using histologic
and chemical analysis.
Objectives.
identify
quantify
the amount of metal debris
generated by titanium
pedicle screw
instrumentation
evaluate the histologic
response in the spinal
tissues.
23. Conclusions.
Wear debris is generated
by the use of titanium
spinal instrumentation in
patients with a
pseudarthrosis.
These particles activate a
macrophage cellular
response in the spinal
tissues similar to that
seen in surrounding joint
prostheses.
Patients with a solid
spinal fusion have
negligible levels of
particulate matter.
24. Biocompatibility studies of
titanium-based alloy pedicle
screw and
rod system: histological aspects
Kazuhiro Yamaguchi, MD et al, The Spine Journal, 2001
25. Study Design:
Few histological studies of pedicle screw and rod
systems have been done, and spinal surgery with
pedicle screw and rod system is increasing.
Objectives:
To know the biocompatibility of pedicle screw and rod
systems histologically.
Study design/setting:
Titanium-based alloy pedicle screws were removed
from 20 patients. Histological studies of the tissue
response to the screws were performed by light
microscopy.
26. Photograph showing spinal fusion
using the Diapason system.
Histological areas were divided into four
areas.
Area 1, muscle 1 cm posterior from screw.
Area 2, muscle–screw interface.
Area 3, tissue around the screw–rod joints.
Area 4, bone–screw interface.
27. Conclusions:
Titanium-based alloy pedicle screws produced
some metal debris and caused localized
inflammation.
No adverse tissue reaction was observed around
the screws and rods.
Direct contact without any fibrous tissue formation
at the bone–screw interface was observed in some
patients.
A titanium-based alloy pedicle screw and rod
system is considered biocompatible histologically.
28. The effect of spinal
instrumentation particulate wear
debris: an in vivo
rabbit model and applied clinical
study of
retrieved instrumentation cases
Cunningham B. W., et al, The Spine Journal 2003
29. Study design:
The current study was undertaken to determine if:
the presence of spinal instrumentation wear
particulate debris deleteriously influences early
osseointegration of posterolateral bone graft
disrupts an established posterolateral fusion mass.
Objectives:
Using an in vivo animal model,
The first phase (basic science) of this study was to
evaluate the effect(s) of titanium wear particulate on
a posterolateral spinal arthrodesis based on
serological, histological and immunocytochemical
analyses.
The second phase (clinical) was to perform the
same analysis of soft tissue surrounding spinal
instrumentation in 12 symptomatic clinical patients.
30. Conclusions:
– Titanium particulate debris introduced at the level
of a spinal arthrodesis elicit:
a cytokinemediated particulate-induced response
favoring:
proinflammatory infiltrates,
increased expression of intracellular TNF-a,
increased osteoclastic activity and
cellular apoptosis.
This is the first basic scientific study and the first clinical
study demonstrating associations of :
spinal instrumentation particulates wear debris
and increased cytokines
and increased osteoclastic activity.
Osteolysis is the number one cause of failure of
orthopedic implants in the appendicular skeleton.
32. Objective
– to clarify the cause of late operative site pain
by the ultrastructural analysis of the
byproducts of metallic corrosion (stainless
steel) as well as the surrounding soft tissues
33. Results
– No signs of infection were present
– Macrophage counts were most abundant
around pedicular screws when compared to:
around the rods
or around the transverse rod connectors
– Particular debris were more abundant around
the rods and transverse connectors
34. Conclusions
– The reaction to particulate metallic debris
from stainless steel implants may be a
probable cause of
Late Operative Site Pain
– There were not findings suggesting the
presence of infection, although the presence
of low-grade infection could not be ruled out
35. Is galvanic corrosion between
titanium alloy and stainless
steel spinal
implants a clinical concern?
Hassan Serhan, PhD, et al, The Spine Journal 4 (2004)
36. BACKGROUND CONTEXT:
– Surgeons are hesitant to mix components
made of differing metal classes for fear of
galvanic corrosion complications.
– However, in vitro studies have failed to show
a significant potential for galvanic corrosion
between titanium and stainless steel, the two
primary metallic alloys used for spinal
implants.
– Galvanic corrosion resulting from metal
mixing has not been described in the literature
for spinal implant systems.
37. METHODS:
– Each construct was immersed in phosphate-buffered
saline (pH 7.4) at 37 C and tested in
cyclic compression.
– The samples were then removed and
analyzed visually for evidence of corrosion.
– In addition, scanning electron microscopy
(SEM) and energy dispersive spectrometry
(EDS) were used to evaluate the extent of
corrosion at the interconnections.
38. Setup of test construct
according to ASTM
F1717 and evidence of
corrosion at implant
component interfaces.
Two constructs in this
study consisted of
titanium alloy rods and
pedicle screws with
mixed titanium alloy and
stainless steel rod–
screw connectors and
transverse rod connector
components, as shown
with arrows.
39. Setup of test construct
according to ASTM
F1717 and evidence of
corrosion at implant
component interfaces.
Two constructs in this
study consisted of
stainless steel rods and
pedicle screws with
mixed titanium alloy and
stainless steel rod–
screw connectors and
transverse rod connector
components, as shown
with arrows.
40. CONCLUSIONS:
– The results from this study indicate that when
loaded dynamically in saline, stainless steel
implant components have a greater
susceptibility to corrosion than titanium.
– Furthermore, the galvanic potential between
the dissimilar metals does not cause a
discernible effect on the corrosion of either.
– Although the mixture of titanium alloy with
stainless steel is not advocated, the results of
this study suggest that galvanic corrosion is
less pronounced in SS-Ti mixed interfaces
than in all stainless steel constructs.
44. Electron Microprobe Analysis
and Tissue Reaction around
Titanium Alloy Spinal Implants
Hee-Dong Kim et al, Asian Spine Journal 2007
45. Study Design:
– A retrospective study of tissue surrounding
titanium alloy spinal implants was performed
using histological and electron microprobe
analysis.
Purpose:
– To identify the metal debris generated by
spinal implants, and then to evaluate the
electron microprobe analysis results and the
histological response of soft tissue
surrounding the spinal implants.
46. Results:
– There were metal particles in the soft tissue in 70% of
the cases.
– Histological finding observed mild chronic
inflammation surrounding the deposition of the metal
particles.
– Scanning electron microscopy of the specimens
showed metallic debris within the tissue and mapping
of the metallic particles revealed the distribution of
titanium in the tissue.
– 90% of patients had successful relief of back pain
after removing the spinal implants.
– Improvement of the back pain may be an association
macrophage response rather than the metal particle.
47. (A) Operative finding shows
local discolorization of the soft
tissues around spinal implant
(Case 2).
(B) Histologic finding reveals
obvious metallosis with black
staining of the tissue.
(C) Scanning electron
microscopy view of specimen
shows the metallic debris within
tissue(×1,000) and mapping of
the metallic particles shows the
distributions of the titanium in
the tissue.
(D) Quantitative analysis of the
metallic debris of specimen was
done with energy dispersive X-ray
spectrometer.
48. (A) Metallic debris was
identified in the dense
connective tissue and the
anti Cotrel-Dubousset 68
positive macrophages
were observed at tissue
adjacent to the metal
particles (Avidin-biotin
complex, ×100).
(B) Macrophages as
stained positive by anti
CD 68 marker (Avidin-biotin
complex, ×200,
Case 5).
49. Conclusions:
– The presence of metallic particles generated
from spinal implants may serve as the
impetus for a late-onset inflammatory
response and late operative site pain.
52. The mobile construct always was encapsulated by a demarcation membrane with a
definite synovial lining.
53. The bone at the base of the transverse process
as it is rubing against the elastic and moving polycarbonate – urethan spacer – sleeve
was covered with organised, multilayered cartilage
that must have formed by some type of periosteal metaplasia
54. Another favourable observation was
the complete absence of cellular reaction to the PET cord
as well as the virtual absence of particle abrasion
and giant cell i.e. phagocyte reaction.
57. CCoonncclluussiioonn
TThhee ppoollyyoolleeffiinn rruubbbbeerr
ppaarrttiicclleess iinndduuccee oonnllyy
llooccaalliizzeedd ttiissssuuee
rreessppoonnssee tthhaatt iiss
ccoonnssiisstteenntt wwiitthh aa
nnoorrmmaall ffoorreeiiggnn bbooddyy
rreeaaccttiioonn ttoo llaarrggee
nnoottooxxiicc ppaarrttiicclleess..
Dura (arrow) surrounding the
spinal cord at S2 of a sheep
3 months after application of
polyolefin rubber particles.
There is focal thickening of the dura
by reactive fibro – adipose tissue
64. With the introduction of
modular artificial disc
replacements and
new materials for
orthopedic spinal
implants,
the effects of implant-fretting
corrosion on
local spinal and
systemic tissues
will remain a clinical
concern.
65. The presence of
titanium particulate
debris, secondary to
motion between spinal
implants, may serve
as:
the impetus for
late-onset
inflammatory-infectious
complications
and
long-term osteolysis
of an established
posterolateral fusion
mass in the clinical
setting.
Γιατί χρειάζεται αυτή η προστατευτική επεξεργασόια
Σημαντικο να θυμηθουμε ο΄τι οι επιφανειακέσ αλλοιώσεισ υλικών προέρχονται από πολλαπλούσ μηχανισμούσ
Και ότι τα παραπανω φαινόμενα μπορεί να λαμβανουν χωρα ταυτοχρονα
…..και διαφορετικής τελικής επιφάνειας : passivated versus anodised